The invention relates to a color display device comprising a substrate on which a black-matrix layer having apertures is provided, said color display device having a phosphor pattern of phosphor regions containing phosphors for emitting, in operation, red, blue and green light through the apertures in the black-matrix layer, with color-filter layers extending between the phosphor regions and the substrate.
Color display devices of the type mentioned in the opening paragraph are used, inter alia, in television receivers and computer monitors.
A color display device of the type mentioned in the opening paragraph is known. Said known color display device comprises a phosphor pattern which includes sub-patterns of phosphor regions luminescing red, green and blue light (hereinafter also referred to as "red", "green" and "blue" phosphors) and it further comprises a black matrix. A black matrix is a black layer provided with apertures or a system of black stripes on the substrate and (in part) between the phosphor regions of which the phosphor pattern is made up, which black-matrix layer improves the contrast of the picture displayed. The black matrix is provided with apertures in which colored layers (also referred to as color-filter layers) are provided, and a phosphor region of a corresponding color is deposited on said colored layers. The color-filter layer absorbs incident light of different wavelengths than the light emitted by the relevant phosphor. This leads to a reduction of the diffuse reflection of incident light and to an improved contrast of the picture displayed. In addition, the color-filter layer (for example a "red" layer) may absorb a part of the radiation emitted by the "red" phosphor, namely the part having wavelengths outside the red portion of the visible spectrum. By virtue thereof, the color point of the red phosphor is improved. The known color display device comprises a color-filter layer for each of the phosphors (red, green and blue). For clarity, it is observed that "red", "blue" and "green" color-filter regions have a relatively high transmission for, respectively, red, blue and green light. The color indication for the color-filter layers relates to the transmission properties of the filters, not to their color.
The known color display device has a number of shortcomings; in particular, the percentage of rejects, that is, the percentage of cathode ray tubes which do not meet the quality requirements, form a problem. Rejects lead to an increase of the cost price of the cathode ray tube and cause environmental problems. The rejected tubes have to be processed in an environmentally friendly manner.